Experimental probability is different from probability. Probability is what you could expect to happen, and experimental probability is what you observe during an experiment. Because a coin has 2 sides, the probability of it being heads is 1/2. This is because there is only 1 'heads' on the coin, but there are two sides to the coin.

The experimental probability in this case would be the number of favorable outcomes divided by the number of total outcomes. Heads occured 487 times, and there were 1000 total outcomes. Thus, the experimental probability in this case is 487/1000. this can allso be written as .487